1. Field of the Invention
The present invention relates to a pulse tube refrigerator adapted to generate the cold at an endothermic portion by connecting a cold accumulator and a pulse tube to each other so as to supply and discharge gas to and from a compressor, and more specifically to a double inlet pulse tube refrigerator adapted to switch gas supply from a compressor to a high-temperature side of a pulse tube.
2. Description of Prior Art
Conventionally, as a pulse tube refrigerator which is capable of obtaining a lower attainable temperature there has been proposed a double inlet pulse tube refrigerator illustrated in FIG. 4 (disclosed in the scientific essay "CRYOGENICS" September 1990).
In this double inlet pulse tube refrigerator, a low-temperature end (51) of a pulse tube (50) is communicated with a low temperature end (53) of a cold accumulator (52) through an endothermic connection pipe (54) serving as a cold head so that gas to be supplied from a compressor (55) to a high-temperature end (57) of the cold accumulator (52) through a refrigerant gas passage (56) can be introduced from the low-temperature end (51) of the pulse tube (50) toward a high-temperature end (58) thereof through the cold accumulator (52) and the endothermic connection pipe (54), a phase shifter comprising a needle valve (59) and a buffer tank (60) is arranged in the high-temperature end (58) of the pulse tube (50), a branch gas passage (61) branched off from the refrigerant gas passage (56) is connected to a passage portion between the high-temperature end of the pulse tube (50) and the buffer tank (60), a needle valve (62) is arranged in the branch gas passage (61), and water coolers (63) (64) are disposed at the high-temperature ends of the cold accumulator (52) and the pulse tube (50) so as to apply a water cooling to the high-temperature end portions of the cold accumulator (52) and the pulse tube (50).
3. Problems Presented by the Prior Art
In the above-mentioned double inlet pulse tube refrigerator, since the buffer tank (60) is so arranged as to be communicated with the high-temperature end (58) of the pulse tube (50), there is a problem that the whole of the refrigerator becomes large in size. Further, since the needle valve (59) is disposed between the high-temparature end of pulse tube (50) and the buffer tank (60) and the needle valve (62) is arranged in the branch gas passage (61) which connects a passage portion between the high-temperature end of the pulse tube (50) and the buffer tank (60) to the refrigerant gas passage (56), there is also such a problem that the gas flow is disturbed by the needle valves (59)(62). Further, in this double inlet pulse tube refrigerator, since a reciprocating type compressor section is in rigid contact with a cold generating section so that vibration of the compressor is transmitted to the cold generating section, there is also a problem that this refrigerator can not be applied for cooling such machines and component members as to hate the vibrations.
The present invention is directed to solving those problems. It is an object of the present invention to provide a pulse tube refrigerator which doesn't need a buffer tank, is small in size and light in weight, can obtain a low attainable temperature and has a high cooling efficiency, and vibrates extremely a little.